1. Preheat oven to 200⁰C.
2. Place water, sugar and butter in a pot and bring to boil.
3. Remove from heat and add in the flour. Stir with a wooden spoon until combined.
4. Return to the heat and stir constantly until the dough comes away from the side of the pot and form a smooth ball.
5. Transfer the dough into a mixer and beat with the paddle attachment to release the steam for about 3 minutes.
6. Once the dough is lukewarm, add the 4 eggs gradually and beat until a smooth and thick paste is formed.
7. Pipe the paste on a baking sheet and brush the top with a lightly beaten egg yolk using a pastry brush.
8. Bake for 15 minutes at 200⁰C then bring it down to 170⁰C for a further 30 minutes.

Method - Filling:

1. Whip cream until stiff peak and pipe a doughnut shape inside the cooled cream puff.
2. Pipe the kaya in the middle of the whipped cream.
3. Brush melted butter on top of the cream puff then sprinkle the desiccated coconut over it.